MRNA

Definition

mRNA, or messenger RNA, is a single-stranded molecule that conveys genetic information from DNA to the ribosome, where proteins are synthesized. This process is essential for the expression of genes and plays a critical role in the central dogma of molecular biology, which describes how genetic information flows from DNA to RNA and then to proteins. mRNA acts as a template that carries the coded instructions necessary for assembling amino acids into proteins, making it a vital player in cellular function.

5 Must Know Facts For Your Next Test

1. mRNA is synthesized in the nucleus during transcription and then transported to the cytoplasm for translation.
2. The sequence of nucleotides in mRNA is complementary to the DNA template strand from which it is transcribed.
3. mRNA can undergo processing, including capping and polyadenylation, before it leaves the nucleus, which helps stabilize the molecule and regulate its translation.
4. Different types of mRNA exist, such as coding mRNA, which contains instructions for protein synthesis, and non-coding mRNA, which has regulatory functions.
5. mRNA has a relatively short lifespan in cells, allowing for precise control over protein production based on cellular needs.

Review Questions

• How does mRNA relate to the processes of transcription and translation in protein synthesis?
  • mRNA is produced during transcription when DNA is copied into a complementary RNA sequence. This mRNA then travels to ribosomes in the cytoplasm where translation occurs. During translation, ribosomes read the mRNA sequence and assemble amino acids into proteins according to the instructions carried by the mRNA, completing the flow of genetic information described by the central dogma.
• Discuss the significance of mRNA processing in eukaryotic cells and how it affects gene expression.
  • In eukaryotic cells, mRNA undergoes several processing steps before it is translated. This includes capping at the 5' end and polyadenylation at the 3' end, which enhance mRNA stability and facilitate its export from the nucleus. Additionally, splicing removes introns from pre-mRNA to produce a mature transcript that accurately reflects the coding sequences. These processing events are crucial for regulating gene expression and ensuring that only properly modified mRNAs are translated into proteins.
• Evaluate how mutations in mRNA can impact protein synthesis and overall cellular function.
  • Mutations in mRNA can lead to changes in the codon sequence that affect protein synthesis by altering amino acid sequences. Such mutations may result in nonfunctional proteins or proteins with altered functions, which can disrupt cellular processes. For instance, a missense mutation may lead to a single amino acid change that could impair enzyme activity or structural integrity. In some cases, mutations can create stop codons that truncate protein synthesis entirely, leading to significant cellular dysfunction or disease states.

Related terms

Transcription: The process by which the genetic information in DNA is copied into mRNA.

Ribosome: The cellular structure where protein synthesis occurs, reading the sequence of mRNA to assemble amino acids into proteins.

Translation: The process by which ribosomes decode mRNA to synthesize proteins, translating the genetic code into functional molecules.